Production process of heavy calcium carbonate with low fine powder content and low oil absorption value

Abstract

The invention discloses a low-fine-powder-content and low-oil-absorption-value heavy calcium carbonate production technology, and belongs to the technical field of heavy calcium carbonate production technologies, and the technology comprises the following steps: S1, carrying out process control on the heavy calcium carbonate production technology by using an intelligent grinding system, firstly controlling the rotating speed of centrifugal grinding equipment, operating within the range of 65-75% of the critical rotating speed, and then controlling the rotating speed of the centrifugal grinding equipment; in the grinding process, the maximum particle size of the materials meets the preset D100 requirement firstly, then the rotating speed of centrifugal grinding equipment is slowed down, the grinding time is prolonged, and the particle size of the materials is accurately controlled; and S2, when the particle size of the material is detected to be close to the preset minimum value, the rotating speed of the centrifugal grinding equipment is further slowed down, the grinding time is prolonged, and the particle size of the material is more accurately controlled. The particle size distribution is better controlled, excessive grinding is avoided, the particle size of the material is smaller than a preset minimum value, and the production quality is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of heavy calcium carbonate production process, in particular to a low-fines-content and low oil absorption value heavy calcium carbonate production process. BACKGROUND

[0002] Heavy calcium carbonate is a kind of calcium carbonate powder directly obtained by mechanically crushing natural minerals such as calcite, marble, and chalk. Its preparation process is a physical method and does not involve chemical reactions. Since it is directly obtained by crushing natural minerals, its particle shape is irregular, the surface is rough, the particle size distribution is wide, the oil absorption value is low, the filling performance is good, and the bulk density is large (usually 0.8-1.3 g / cm³), so it is called "heavy". Light calcium carbonate is a kind of calcium carbonate prepared by chemical synthesis method. Usually, limestone is calcined to generate calcium oxide and carbon dioxide, then calcium oxide is reacted with water to generate calcium hydroxide, and finally carbon dioxide is introduced to precipitate calcium carbonate. Its preparation process is a chemical method.

[0003] The preparation of traditional heavy calcium carbonate powder usually adopts the method of grinding + classification. However, taking the product with 2500 mesh as an example, the proportion of heavy calcium carbonate powder with particle size less than 2 μm is about 50%, which is a large proportion. Since the small particle heavy calcium carbonate powder needs more resin to wrap, more resin will be consumed when producing membrane products. In order to maintain the mechanical properties and processing performance of the product, the addition amount of heavy calcium carbonate powder may be limited, so that the relatively low-priced calcium carbonate powder cannot be fully utilized to replace part of the resin, resulting in cost increase, or the addition amount of calcium carbonate powder is limited, resulting in product cost increase.

[0004] In the traditional grinding process, the movement of the material is usually disordered, and the particles collide randomly, resulting in low grinding efficiency and easy over-grinding.

[0005] Disordered collision can cause the following problems: over-grinding: part of the material may be ground too fine due to frequent collision, exceeding the target particle size range. Low grinding efficiency: disordered collision can cause energy waste and reduce the grinding efficiency. Non-uniform particle size distribution: disordered collision can cause wide particle size distribution of the material, making it difficult to achieve ideal uniformity. SUMMARY

[0006] In order to overcome the shortcomings of the prior art, the purpose of the present application is to provide a low-fines-content and low oil absorption value heavy calcium carbonate production process, which better controls the particle size distribution, avoids over-grinding, and improves the production quality.

[0007] The purpose of the present application is achieved by the following technical solutions: The low-fines-content and low oil absorption value heavy calcium carbonate production process comprises the following steps: S1, using the intelligent grinding system to control the process of the heavy calcium carbonate production process, first controlling the speed of the centrifugal grinding equipment to run in the range of 65%-75% of the critical speed, so that the maximum particle size of the material in the grinding process meets the preset D100 requirement, then slowing down the speed of the centrifugal grinding equipment, prolonging the grinding time, and accurately controlling the particle size of the material; S2, when detecting that the particle size of the material approaches the preset minimum value, further slowing down the speed of the centrifugal grinding equipment, prolonging the grinding time, and more accurately controlling the particle size of the material; S3, when detecting that the particle size of the material is less than the preset minimum value, the centrifugal grinding equipment stops working, and the low-fines-content, low-oil-absorption-value heavy calcium carbonate is obtained; The control system integrates PLC (programmable logic controller) or industrial computer, which is used for receiving particle size detection data and automatically adjusting the speed of the centrifugal grinding equipment and automatically adjusting the grinding parameters according to the preset control logic, for receiving particle size detection data; The particle size detection system is used for real-time detection of the particle size distribution of the ground material; The data acquisition module is used for real-time acquisition and transmission of the particle size detection data of the laser particle size instrument to the control system; The servo motor is used for adjusting the speed of the centrifugal grinding equipment according to the instruction of the control system.

[0008] Further, the intelligent grinding system further comprises a feedback and monitoring system, and the feedback and monitoring system comprises: A real-time monitoring interface is used to display the particle size detection data and the running state of the centrifugal grinding equipment, so as to facilitate the operator to monitor and adjust, and control the speed of the grinding disc; An alarm system is used to issue an alarm when the particle size distribution exceeds the set range or the equipment fails.

[0009] Further, the material is pretreated, including: pre-breaking the material to reduce the grinding load; if the moisture content of the material is high, drying treatment is performed to reduce the adhesion of the material during grinding.

[0010] Further, the pre-breaking treatment adopts a hammer crusher, a roller crusher or a vertical shaft super fine crusher to break the material, so that the particle size of the material is reduced to less than 5-8 mm.

[0011] Further, the drying treatment adopts hot air drying, microwave drying or other suitable drying technology to reduce the moisture content of the material.

[0012] Further, the grinding cavity of the centrifugal grinding device is a cylindrical structure, a material feeding port is arranged at the top of the grinding cavity, the material feeding port is communicated with one end of a material conveying pipeline through a rotary joint, the other end of the material conveying pipeline is communicated with a discharge port of a feeding hopper, and an air inlet of a blower is communicated with an intermediate position of the material conveying pipeline.

[0013] Further, the grinding medium used in the centrifugal grinding device is a common carbon steel ball.

[0014] Further, a discharge port is arranged at the eccentric position of the bottom of the cylindrical structure, and a discharge valve is arranged at the discharge port.

[0015] Further, when it is detected that the particle size of the material is less than a preset minimum value, the minimum value is 2 microns.

[0016] Further, the preset D100 requirement is that the maximum particle size of the material during the grinding process is 10 microns.

[0017] Compared with the prior art, the beneficial effects of the present application are that: The low-fine-powder-content and low-oil-absorption-value heavy calcium carbonate production process provided by the present application has the following beneficial effects: the control system is integrated with a PLC (programmable logic controller) or an industrial computer, is used for receiving particle size detection data and automatically adjusting the rotating speed of the centrifugal grinding device and automatically adjusting the grinding parameters according to a preset control logic, the rotating speed can be increased at the beginning, the D100 can be ensured to meet the requirements in the material grinding process, and then the rotating speed is slowed down, the grinding time is prolonged, and the particle size of the material is better controlled; a material feeding port is arranged at the top of the grinding cavity, the material feeding port is communicated with one end of a material conveying pipeline through a rotary joint, the other end of the material conveying pipeline is communicated with a discharge port of a feeding hopper, and an air inlet of a blower is communicated with an intermediate position of the material conveying pipeline, the installation mode can ensure that airflow is formed before the material enters the grinding area, so that the material is better brought into the grinding device, and the airflow and the material are mixed and then enter the grinding device, so that the material is uniformly distributed. The airflow forms a rotating motion in the grinding device, and the fine powder and the coarse powder are separated by using the drag force of the airflow, the separation process ensures that only unqualified fine powder (fine powder below 2 microns) is discharged, and the coarse powder returns to the grinding area for continuous grinding. The particle size distribution is accurately controlled, the fine powder below 2 microns can be more efficiently separated out, the proportion of particles less than 2 microns is reduced, and the content of the particles in the final product is reduced. DETAILED DESCRIPTION

[0018] The present application will be further described below in combination with specific embodiments, and it should be noted that the embodiments described below or the technical features thereof can be combined in any manner to form new embodiments without conflict. EMBODIMENT

[0019] The production process of the low-fines-content and low oil absorption value heavy calcium carbonate provided by the embodiment comprises the following steps: S1, using an intelligent grinding system to control the process of the production process of heavy calcium carbonate, first controlling the speed of the centrifugal grinding equipment to run in the range of 65%-75% of the critical speed, so that the maximum particle size of the material in the grinding process meets the preset D100 requirement, the preset D100 requirement is that the maximum particle size of the material in the grinding process is 10μm, then slowing down the speed of the centrifugal grinding equipment, prolonging the grinding time, and accurately controlling the particle size of the material; This step ensures that the initial particle size of the material is within a controllable range.

[0020] According to the particle size detection result, the speed of the centrifugal grinding equipment is automatically adjusted to change the centrifugal force. For example, when it is detected that there are too large particles in the particle size distribution, the speed is appropriately increased to enhance the grinding effect.

[0021] S2, when it is detected that the particle size of the material approaches the preset minimum value, the minimum value is 2μm, the speed of the centrifugal grinding equipment is further slowed down, the grinding time is prolonged, and the particle size of the material is more accurately controlled; reducing the speed can make the material in the grinding process receive a more gentle grinding action, thereby realizing more fine particle size control.

[0022] S3, when it is detected that the particle size of the material is less than the preset minimum value, the minimum value is 2μm, the centrifugal grinding equipment stops working, and the low-fines-content and low oil absorption value heavy calcium carbonate is obtained; reducing the speed can make the material in the grinding process receive a more gentle grinding action, thereby realizing more fine particle size control.

[0023] The control system integrates PLC (Programmable Logic Controller) or industrial computer, which is used to receive particle size detection data and automatically adjust the speed of the centrifugal grinding equipment and automatically adjust the grinding parameters according to the preset control logic, and is used to receive particle size detection data; The particle size detection system is used to detect the particle size distribution of the ground material in real time; The data acquisition module is used to collect and transmit the particle size detection data of the laser particle size instrument to the control system in real time; The servo motor is used to adjust the speed of the centrifugal grinding equipment according to the instructions of the control system.

[0024] Further, the intelligent grinding system further comprises a feedback and monitoring system, which comprises: A real-time monitoring interface is used to display the particle size detection data and the running state of the centrifugal grinding equipment, so as to facilitate the operator to monitor and adjust, and control the speed of the grinding disc; An alarm system is used to issue an alarm when the particle size distribution exceeds the set range or the equipment fails.

[0025] By controlling the trajectory of the material with centrifugal force, the following advantages can be achieved: Directed collision: The material moves along a specific trajectory, making the collision more orderly and energy utilization more efficient.

[0026] Reducing over-grinding: By controlling the intensity and frequency of collisions, the material is prevented from being over-grounded.

[0027] Uniform particle size distribution: Directed collision can more accurately control the particle size of the material, reducing the dispersion of the particle size distribution. The airflow forms a rotating motion in the grinding equipment, using the drag force of the airflow to separate the fine powder from the coarse powder. This separation process ensures that only unqualified fine powder (2 μm or less) is discharged, while the coarse powder returns to the grinding area for further grinding.

[0028] In this embodiment, the material is pretreated, including: pre-breaking the material to reduce the grinding load; if the moisture content of the material is high, drying treatment is carried out to reduce the adhesion of the material during grinding. The purpose of this step is: the grinding load in the fine grinding stage refers to the energy and time required by the centrifugal grinding equipment when processing the material. After pre-breaking, the particle size of the material is reduced, and the fine grinding equipment can grind more efficiently, thereby reducing the grinding load. Reducing the grinding load not only improves the grinding efficiency, but also reduces the wear and energy consumption of the equipment.

[0029] Specifically, the pre-breaking treatment uses a hammer crusher, a roller crusher or a vertical shaft super fine crusher to break the material, reducing the particle size of the material to less than 5-8 mm.

[0030] Specifically, the drying treatment uses hot air drying, microwave drying or other suitable drying techniques to reduce the moisture content of the material.

[0031] Specifically, the grinding chamber of the centrifugal grinding equipment is a cylindrical structure, and the top of the grinding chamber is provided with a material feeding port. The material feeding port is communicated with one end of a material conveying pipeline through a rotary joint, and the other end of the material conveying pipeline is communicated with the discharge port of a feeding hopper. The intermediate position of the material conveying pipeline is communicated with the air inlet of a blower. The cylindrical structure of the grinding chamber can ensure that the material is uniformly stressed during grinding, reducing the accumulation and uneven grinding of the material. A rotary joint is installed between the material conveying pipeline and the material feeding port. One end of the rotary joint is fixed with the material conveying pipeline, and the other end rotates with the centrifugal grinding equipment, which does not affect the centrifugal grinding equipment, ensuring the continuous and stable supply of airflow in the material conveying pipeline.

[0032] The airflow forms a rotating motion in the separator, using centrifugal force to separate the fine powder from the coarse powder. This separation process ensures that only unqualified fine powder is discharged, while the coarse powder returns to the grinding area for further grinding.

[0033] In this embodiment, the grinding media used in the centrifugal grinding device are ordinary carbon steel balls. Lower hardness media (such as steel balls) are suitable for soft materials. Calcium carbonate ore has low hardness, and medium hardness media can be selected.

[0034] Further, a discharge port is arranged at the eccentric bottom of the cylindrical structure, and a discharge valve is installed at the discharge port. The separated unqualified fine powder (fine powder below 2 μm) is recycled and treated as raw material for other low-end products, reducing waste.

[0035] Centrifugal force: centrifugal force is an inertial force generated by an object in rotational motion, which always points vertically to the rotation axis. The material and grinding media on the high-speed rotating rotor are subjected to centrifugal force, which is thrown to the grinding chamber wall, collides and rubs with the grinding media or chamber wall, and realizes crushing. Due to the directionality of centrifugal force, the movement trajectory of the material in the grinding chamber is controllable, reducing excessive grinding caused by disordered collision. The size of the centrifugal force depends on the rotor speed and rotor radius, and the grinding intensity can be controlled by adjusting the rotor speed. By adjusting the size of the centrifugal force, the material can be classified. Larger particles are left in the grinding area for further crushing due to larger centrifugal force, while smaller particles are carried out by the airflow.

[0036] Centrifugal grinding machine: a centrifugal grinding machine with variable frequency speed regulation function is selected, which can adjust the speed according to the needs.

[0037] Particle size monitoring: after each grinding stage, a laser particle size analyzer or screening equipment is used to monitor the particle size distribution to ensure that the target particle size is reached. If there are too large particles in the particle size distribution, the grinding time can be appropriately increased or the centrifugal force can be adjusted.

[0038] Synergistic effect of centrifugal force and airflow: in the centrifugal grinding machine, the main function of the airflow is to carry the fine powder out of the grinding area, and to help the coarse particles stay in the grinding area for further crushing. The airflow produces centripetal force and drag force on the particles, which interacts with the centrifugal force. For fine particles, the drag force of the airflow is relatively large, which can overcome the centrifugal force and be carried out with the airflow; while for coarse particles, the centrifugal force is larger, and the airflow is difficult to carry them out.

[0039] Suitable airflow speed can ensure that fine powder is effectively carried out, while avoiding excessive interference with the centrifugal force of coarse particles. By monitoring the particle size detection data in real time during the grinding process, the airflow speed is adjusted to ensure that only unqualified fine powder (fine powder below 2 μm) is discharged, while coarse powder returns to the grinding area for further grinding.

[0040] The above embodiments are only preferred embodiments of the present application, and cannot be used to limit the scope of protection of the present application. Any non-essential changes and substitutions made by those skilled in the art based on the present application are within the scope of the present application.

Claims

1. A process for the production of low fines content, low oil absorption value heavy calcium carbonate, characterized in that, The method comprises the following steps: S1, using an intelligent grinding system to control the process of heavy calcium carbonate production, first controlling the speed of the centrifugal grinding equipment to run in the range of 65%-75% of the critical speed, so that the maximum particle size of the material in the grinding process meets the preset D100 requirement, then slowing down the speed of the centrifugal grinding equipment to prolong the grinding time and accurately control the particle size of the material; S2, when the particle size of the material is detected to be close to the preset minimum value, further slowing down the speed of the centrifugal grinding equipment to prolong the grinding time and more accurately control the particle size of the material; S3, when the particle size of the material is detected to be less than the preset minimum value, the centrifugal grinding equipment stops working to obtain the heavy calcium carbonate with low fine powder content and low oil absorption value; The intelligent grinding system comprises a control system, a particle size detection system, a data acquisition module and a servo motor; The control system is used to receive particle size detection data and automatically adjust the speed of the centrifugal grinding equipment and automatically adjust the grinding parameters according to the preset control logic; The particle size detection system is used to detect the particle size distribution of the ground material in real time; The data acquisition module is used to collect and transmit the particle size detection data of the laser particle size instrument to the control system in real time; The servo motor is used to adjust the speed of the centrifugal grinding equipment according to the instructions of the control system.

2. The low-fines, low oil absorption value, heavy calcium carbonate production process of claim 1, wherein, The intelligent grinding system further comprises a feedback and monitoring system, which comprises: A real-time monitoring interface for displaying particle size detection data and the running state of the centrifugal grinding equipment, facilitating the operator to monitor and adjust the speed of the grinding disc; An alarm system for issuing an alarm when the particle size distribution exceeds the set range or the equipment fails.

3. The low-fines, low oil absorption value, heavy calcium carbonate production process of claim 1, wherein, The material is pretreated, including: pre-breaking the material to reduce the grinding load; if the moisture content of the material is high, drying treatment is performed to reduce the adhesion of the material during grinding.

4. The process for producing low-fines, low oil absorption value ground calcium carbonate as claimed in claim 3, wherein, The pre-breaking treatment uses a hammer crusher, a roller crusher or a vertical shaft super fine crusher to break the material to reduce the particle size to less than 5-8 mm.

5. The process for producing low-fines, low oil absorption value ground calcium carbonate as claimed in claim 3, wherein, The drying treatment uses hot air drying, microwave drying or other suitable drying techniques to reduce the moisture content of the material.

6. The low-fines, low oil absorption value, heavy calcium carbonate production process of claim 1, wherein, The grinding cavity of the centrifugal grinding equipment is a cylindrical structure, the top of the grinding cavity is provided with a material feeding port, the material feeding port is communicated with one end of a material conveying pipeline through a rotary joint, the other end of the material conveying pipeline is communicated with the discharge port of a feeding hopper, and the middle position of the material conveying pipeline is communicated with the air inlet of a blower. The material conveying pipeline is used to introduce the airflow generated by the blower into the grinding cavity to carry the material into the grinding area.

7. The low-fines, low oil absorption value ground calcium carbonate production process of claim 6, wherein, The grinding medium used in the centrifugal grinding equipment is a common carbon steel ball.

8. The low-fines, low oil absorption value ground calcium carbonate production process of claim 7, wherein, A discharge port is arranged at the eccentric position of the bottom of the cylindrical structure, and a discharge valve is installed at the discharge port.

9. The low-fines, low oil absorption value, ground calcium carbonate production process as claimed in claim 1, wherein, When the particle size of the material is detected to be less than the preset minimum value, the minimum value is 2 μm.

10. The low-fines, low oil absorption value, heavy calcium carbonate production process of claim 1, wherein, The preset D100 requirement is that the maximum particle size of the material in the grinding process is 10 μm.